The present invention relates to a preventive or therapeutic agent for inflammatory bowel disease comprising an interleukin-6 (IL-6) antagonist as an active ingredient. The present invention also relates to a preventive or therapeutic agent for Crohn""s disease or ulcerative colitis comprising an IL-6 antagonist as an active ingredient.
IL-6 is a cytokine which is also called B cell stimulating factor 2 (BSF2) or interferon xcex22. IL-6 was discovered as a differentiation factor involved in the activation of B-lymphocytic cells (Hirano, T. et al., Nature (1986) 324, 73-76). Thereafter, it was found to be a multifunctional cytokine that influences various functions of cells (Akira, S. et al., Adv. in Immunology (1993) 54, 1-78). IL-6 has been reported to induce the maturation of T-lymphocytic cells (Lotz, M. et al., J. Exp. Med. (1988) 167, 1253-1258).
IL-6 transmits its biological signal through two proteins on the cell. One of them is IL-6 receptor, a IL-6-binding protein with a molecular weight of about 80 kD, (Taga, T. et al., J. Exp. Med. (1987) 166, 967-981; Yamasaki, K. et al., Science (1987) 241, 825-828). IL-6 receptor exists not only in the membrane-bound form with transmembrane domain expressed on the cell surface but also as a soluble IL-6 receptor consisting mainly of the extracellular region.
The other is a membrane-bound protein gp130 having a molecular weight of about 130 kD that is involved in non-ligand-binding signal transduction. IL-6 and IL-6 receptor form the IL-6/IL-6 receptor complex, which after binding to gp130 transmits its biological signal to the cell (Taga, T. et al., Cell (1989) 58, 573-581).
IL-6 antagonists are substances that inhibit the transduction of biological activity of IL-6. As the IL-6 antagonists, there have been known so far antibody against IL-6 (anti-IL-6 antibody), antibody against IL-6 receptor (anti-IL-6 receptor antibody), and antibody against gp130 (anti-gp130 antibody), altered IL-6, partial peptides of IL-6 or IL-6 receptor and the like.
Anti-IL-6 receptor antibody has been described in several reports (Novick D. et al., Hybridoma (1991) 10, 137-146, Huang, Y. W. et al., Hybridoma (1993) 12, 621-630, International Patent Publication WO 95/09873, French Patent Application FR 2694767, U.S. Pat. No. 5,21,628). Humanized PM-1 antibody has been known that was obtained by grafting the complementarity determining region (CDR) of a mouse antibody PM-1 (Hirata, Y. et al., J. Immunology (1989) 143, 2900-2906) to a human template antibody (the International Patent Publication WO 92-19759).
Inflammatory bowel disease (IBD) is a nonspecific inflammation represented by ulcerative colitis and Crohn""s disease. Immunological disturbances have been implicated in the onset of the disease, but that has not led to the elucidation of the etiology. It is believed, however, that monocytes and lymphocytes that clustered at lesion sites are involved in the damages of mucus, and inflammatory mediators, in particular cytokines (such as IL1xcex2, TNFxcex1, and IL-6) are drawing special attention.
For IL-6 among the inflammatory mediators, attention has been given to its relation to the disease status or to whether it could be an specific index for IBD. Serum level of IL-6 increases in both of Crohn""s disease and ulcerative colitis, and the level correlates with the condition of the disease (Holtkamp, W. et al., J. Clin. Gastroenterology (1995) 20, 123-126, Niederau, C. et al., Hepato-Gastroenterology (1997) 44, 90-107). Measurement of amount of IL-6 mRNA in the tissue as PCR (polymerase chain reaction) products has revealed that it well correlated to the disease status of both ulcerative colitis and Crohn""s disease (Stevens, C. et al., Dig. Dis. Sci. (1992) 37, 818-826). On the increase of IL-6 production during active IBD, the mechanism was analyzed and it was found that the amount of production when mononuclear cells in the lamina propria are stimulated by Pokeweed mitogen, are well correlated with the condition of disease (Reinecker, H.-C. et al., Clin. Exp. Immunol. (1993) 94, 174-181).
Thereafter, the correlation of IL-6 production and disease status was observed in the culture of mononuclear cells derived from the lamina propria and the tissue culture of the mucosa from patients. In the former case, it was also shown that the number of cells that produce IL-6 in the mucosal tissue also increased. Among the mononuclear cells the most important IL-6-producing cells are macrophage, and it has been confirmed that there are a great number of CD68-positive macrophages that vigorously produce IL-6 in the lamina propria of the IBD patients in the active stage (Kusugami, K. et al., Dig. Dis. Sci. (1995), 40, 949-959).
It has also been found that the production of IL-6 correlates to the endoscopic observation of patients with Crohn""s disease (Reimund, J.-M. et al., Gut (1996) 39, 684-689). In addition, there are some reports that not only IL-6 but soluble IL-6 receptor concentration in serum well correlates with the disease status (Mitsuyama, K. et al., Gut (1995) 36, 45-49).
For inflammatory mediators other than IL-6, the amount of IL-1xcex2 production is also known to correlate to condition of disease. On the other hand, this is not always true for TNF-xcex1 and the amount of production may tend to be high in low activity in disease condition (Reinecker, H.-C. et al., Clin. Exp. Immunol. (1993) 94, 174-181, Reimund, J.-M. et al., Gut (1996) 39, 684-689).
The current method of treating IBD comprises a combination of diet and medication, with salazosulfapyridine, glucocorticoid, etc. being prescribed. For these drugs, however, there are intolerant patients due to their side effects, and thereby problems occur in terms of a long-term administration.
On the other hand, some trials are going on as a new treatment of IBD that intends to improve disease conditions through the inhibition of cytokine activity. Its main targets are IL-1 and TNF-xcex1 (Van Deventer, S. J. H. Gut (1997) 40, 443-448); for IL-1, an IL-1 receptor antagonist (Cominelli F. et al., Gastroenterology (1992) 103, 65-71) and an IL-1 inhibitor, CGP47969A (Casini-Raggi et al., Gastroenterology (1995) 109, 812-818), and the like are under study on the clinical or the experimental animal level. For TNF-xcex1, specific monoclonal antibody has been administered to patients with Crohn""s disease, in which reduced activity and cured ulcer have been observed (Van Dullemen, H. M. et al., Gastroenterology (1995) 109, 129-135). It was not known, however, that IL-6 antagonist can treat IBD to specifically suppress the biological activity of IL-6.
It is an object of the present invention to provide a preventive or therapeutic agent for inflammatory bowel disease said agent being free of the above-mentioned drawbacks.
Thus, the present invention provides (1) a preventive or therapeutic agent for inflammatory bowel disease comprising an IL-6 antagonist as an active ingredient.
The present invention also provides (2) a preventive or therapeutic agent for inflammatory bowel disease comprising an antibody against IL-6 receptor as an active ingredient.
The present invention also provides (3) a preventive or therapeutic agent for inflammatory bowel disease comprising a monoclonal antibody against IL-6 receptor as an active ingredient.
The present invention also provides (4) a preventive or therapeutic agent for inflammatory bowel disease comprising a monoclonal antibody against human IL-6 receptor as an active ingredient. The monoclonal antibody against human IL-6 receptor is preferably PM-1 antibody.
The present invention also provides (5) a preventive or therapeutic agent for inflammatory bowel disease comprising a monoclonal antibody against mouse IL-6 receptor as an active ingredient. The monoclonal antibody against mouse IL-6 receptor is preferably MR16-1 antibody.
The present invention also provides (6) a preventive or therapeutic agent for inflammatory bowel disease comprising a recombinant antibody against IL-6 receptor as an active ingredient. The recombinant antibody against IL-6 receptor has preferably a constant region (C region) of human antibody.
The present invention also provides (7) a preventive or therapeutic agent for inflammatory bowel disease comprising a chimeric or humanized antibody against IL-6 receptor as an active ingredient.
The present invention also provides (8) a preventive or therapeutic agent for inflammatory bowel disease comprising humanized PM-1 antibody as an active ingredient.
The present invention also provides (9) a preventive or therapeutic agent for Crohn""s disease or ulcerative colitis comprising the IL-6 antagonist described in the above (1) to (8) as an active ingredient.
The present invention also provides (10) an agent for suppressing weight loss in inflammatory bowel disease said agent comprising the IL-6 antagonist described in the above (1) to (8) as an active ingredient.
The present invention also provides (11) an agent for suppressing weight loss in inflammatory bowel disease said agent comprising the IL-6 antagonist described in the above (3) to (8) as an active ingredient.
IL-6 antagonists for use in the present invention may be of any origin, any kind, and any form, as long as they have a preventive or therapeutic effect on inflammatory bowel disease, or an effect of controlling weight loss in inflammatory bowel disease.
IL-6 antagonists block signal transduction by IL-6 and inhibit the biological activity of IL-6. As the IL-6 antagonists, there can be mentioned preferably anti-IL-6 antibody, anti-IL-6 receptor antibody, anti-gp130 antibody, altered IL-6, altered soluble IL-6 receptor, a partial peptide of IL-6 or IL-6 receptor, and a low molecular weight substances having the same activity as these.
Anti-IL-6 antibodies for use in the present invention can be obtained as polyclonal or monoclonal antibodies using a known method. As the anti-IL-6 antibodies for use in the present invention, monoclonal antibodies of, in particular, a mammalian origin, are preferred. Monoclonal antibodies of a mammalian origin include those produced by hybridomas and recombinant antibodies produced by host cell which has been transformed with an expression vector containing genetically engineered antibody genes. These antibodies, via binding to IL-6, block the binding of IL-6 to IL-6 receptor, and thereby blocks signal transduction of the biological activity of IL-6 into the cell.
Examples of such antibodies include MH166 (Matsuda et al., Eur. J. Immunol. (1988) 18, 951-956) and SK2 antibody (Sato, K. et al., The 21st Nihon Mennekigakkai Soukai (General Meeting of the Japan Immunology Society), Academic Record (1991) 21, 166) and the like.
An anti-IL-6 antibody-producing hybridoma can be basically constructed using a known procedure as described below. Thus, IL-6 may be used as a sensitizing antigen in the conventional method of immunization. The immunized cells thus obtained are fused with known parent cells in the conventional cell fusion process, and then monoclonal antibody-producing cells are screened by a conventional screening method to prepare the desired hybridoma.
Specifically, anti-IL-6 antibody may be obtained in the following manner. For example, a human IL-6 for use as a sensitizing antigen to obtain an antibody can be obtained using the IL-6 gene/amino acid sequence disclosed in Eur. J. Biochem (1987) 168, 543-550, J. Immuno. (1988) 140, 1534-1541, or Agr. Biol. Chem. (1990) 54, 2685-2688.
After a suitable host cell is transformed by inserting the IL-6 gene sequence into a known expression vector system, the IL-6 protein is purified from the host cell or the culture supernatant thereof. The purified IL-6 protein can be used as a sensitizing antigen. Alternatively, a fusion protein of the IL-6 protein and another protein may be used as a sensitizing antigen.
Anti-IL-6 receptor antibodies for use in the present invention can be obtained as polyclonal or monoclonal antibodies using a known method. As the anti-IL-6 antibodies for use in the present invention, monoclonal antibodies of, in particular, a mammalian origin, are preferred. Monoclonal antibodies of a mammalian origin include those produced by hybridomas and those produced by host cell which has been transformed with an expression vector containing genetically engineered antibody genes. The antibodies, via binding to IL-6 receptor, inhibit the binding of IL-6 to IL-6 receptor, and thereby block the transduction of the biological activity of IL-6 into the cell.
Examples of such antibodies include MR16-1 antibody (Tamura, T., et al., Proc. Natl. Acad. Sci. USA (1993) 90, 11924-11928), PM-1 antibody (Hirata, et al., J. Immunology (1989) 143, 2900-2906), or AUK12-20 antibody, AUK64-7 antibody or AUK146-15 antibody (International Patent Publication WO 92-19759), and the like. Among them, PM-1 antibody is most preferred.
The hybridoma cell line which produces PM-1 antibody has been internationally deposited under the provisions of the Budapest Treaty as PM-1 on Jul. 10, 1990 with the National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, of 1-3, Higashi 1-chome, Tsukuba-shi, Ibaraki pref., Japan, as FERM BP-2998. In addition, the hybridoma cell line which produces MR16-1 antibody has been internationally deposited under the provisions of the Budapest Treaty as MR16-1 on Mar. 13, 1997 with the National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, of 1-3, Higashi 1-chome, Tsukuba-shi, Ibaraki pref., Japan, as FERM BP-5875.
Hybridoma producing anti-IL-6 receptor monoclonal antibody can be basically constructed using a known procedure as described bellow. Thus, IL-6 receptor is used as a sensitizing antigen according to the conventional method of immunization. The immunized cells thus obtained are fused with known parent cells in a conventional cell fusion process, and then monoclonal antibody-producing cells may be screened by a conventional screening method to prepare a desired hybridoma.
Specifically, anti-IL-6 receptor antibody may be prepared in the following manner. For example, human IL-6 receptor used as a sensitizing antigen for obtaining an antibody can be obtained using the IL-6 receptor gene sequence/amino acid sequence disclosed in European Patent Application EP 325474, and mouse IL-6 receptor can be obtained using that disclosed in Japanese Unexamined Patent Publication (Kokai) 3(1991)-155795.
There are two types of IL-6 receptor proteins: IL-6 receptor expressed on the cell membrane, and IL-6 receptor detached from the cell membrane (soluble IL-6 Receptor) (Yasukawa, K. et al., J. Biochem. (1990) 108, 673-676). Soluble IL-6 receptor antibody consists essentially of an extracellular region of an IL-6 receptor bound to the cell membrane, and thereby is different from a membrane-bound IL-6 receptor in that the latter lacks the transmembrane region or both of the transmembrane region and the intracellular region. As the IL-6 receptor protein, any IL-6 receptor can be used, as long as it can be used a sensitizing antigen for production of the IL-6 receptor antibody for use in the present invention.
After a gene sequence of IL-6 receptor is inserted into a known expression vector system to transform an appropriate host cell, the desired IL-6 receptor protein may be purified from the host cells or a culture supernatant thereof using a known method. The IL-6 receptor protein thus purified may be used as a sensitizing antigen. Alternatively, cells that are expressing IL-6 receptor or a fusion protein of the IL-6 receptor protein and another protein may be used as a sensitizing antigen.
E. coli that has a plasmid pIBIBSF2R containing cDNA encoding human IL-6 receptor has been internationally deposited under the provisions of the Budapest Treaty as HB101-pIBIBSF2R on Jan. 9, 1989 with the National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, of 1-3, Higashi 1-chome, Tsukuba-shi, Ibaraki pref., Japan, as FERM BP-2232.
Anti-gp130 antibodies for use in the present invention can be obtained as polyclonal or monoclonal antibodies using a known method. As the anti-gp130 antibodies for use in the present invention, monoclonal antibodies of, in particular, a mammalian origin, are preferred. Monoclonal antibodies of a mammalian origin include those produced by hybridomas and those produced by host cell which has been transformed with an expression vector containing genetically engineered antibody genes. The antibodies, via binding to gp130, inhibits the binding of IL-6/IL-6 receptor complex to gp130, and thereby blocks the transduction of the biological activity of IL-6 into the cell.
Examples of such antibodies include AM64 antibody (Japanese Unexamined Patent Publication (Kokai) 3(1991)-219894), 4B11 antibody and 2H4 antibody (U.S. Pat. No. 5,571,513), B-S12 antibody and B-P8 antibody (Japanese Unexamined Patent Publication (Kokai) 8(1996)-291199).
A monoclonal antibody-producing hybridoma can be basically created using a known procedure as described below. Thus, gp130 may be used as a sensitizing antigen and is used for immunization in a conventional method for immunization. The immunized cells thus obtained are fused with known parent cells in a conventional cell fusion process, and then monoclonal antibody-producing hybridomas are screened by a conventional screening method to prepare a desired hybridoma.
Specifically, monoclonal antibody may be obtained in the following manner. For example, gp130 used as a sensitizing antigen for antibody generation can be obtained using a gp130 gene sequence/amino acid sequence disclosed in European Patent Application EP 411946.
After inserting the gp130 gene sequence into a known expression vector system, a suitable host cell is transformed with the vector system, and the gp130 protein is purified from the host cell or from the culture supernatant thereof. The purified gp130 receptor protein can be used as the sensitizing antigen. Alternatively, a fusion protein of the gp130 protein and another protein may be used as a sensitizing antigen.
Though mammals to be immunized with a sensitizing antigen are not particularly limited, they are preferably selected in consideration of their compatibility with the parent cell for use in cell fusion. They generally include rodents such as mice, rats, hamsters and the like.
Immunization of animals with a sensitizing antigen is carried out using a known method. A general method, for example, involves an intraperitoneal or subcutaneous administration of a sensitizing antigen to a mammal. Specifically, a sensitizing antigen which has been diluted and suspended in an appropriate amount of phosphate buffered saline (PBS) or physiologic saline etc. is mixed, as desired, with an appropriate amount of a conventional adjuvant, for example Freund""s complete adjuvant. After being emulsified, it is preferably administered to a mammal for several times every 4 to 21 days. Alternatively a suitable carrier may be used at the time of immunization with the sensitizing antigen.
After immunization and the confirmation of the increase in the desired antibody titer in the serum, the immunized cells are taken out from the mammal and are subjected to cell fusion. Preferred immunized cells include in particular the spleen cells.
The mammalian myeloma cells as the other parent cells which are subjected to cell fusion with the above-mentioned immune cells preferably include various known cell lines such as P3X63Ag8.653) (Kearney, J. F. et al., J. Immunol. (1979) 123: 1548-1550), P3X63Ag8U.1 (Current Topics in Microbiology and Immunology (1978) 81: 1-7), NS-1 (Kohler, G. and Milstein, C., Eur. J. Immunol. (1976) 6: 511-519), MPC-11 (Margulies, D. H. et al., Cell (1976) 8: 405-415), SP2/0 (Shulman, M. et al., Nature (1978) 276: 269-270), FO (de St. Groth, S. F. et al., J. Immunol. Methods (1980) 35: 1-21), S194 (Trowbridge, I. S., J. Exp. Med. (1978) 148: 313-323), R210 (Galfre, G. et al., Nature (1979) 277: 131-133) and the like.
Cell fusion between the above immunized cells and the myeloma cells may be essentially conducted in accordance with a known method such as is described in Milstein et al. (Kohler, G. and Milstein, C., Methods Enzymol. (1981) 73: 3-46) and the like.
More specifically, the above cell fusion is carried out in the conventional nutrient broth in the presence of, for example, a cell fusion accelerator. As the cell fusion accelerator, for example, polyethylene glycol (PEG), Sendai virus (HVJ) and the like may be used. In addition, an adjuvant such as dimethyl sulfoxide etc. may be added as desired to enhance the efficiency of fusion.
The preferred ratio of the immunized cells and the myeloma cells to be used is, for example, 1 to 10 times more immunized cells than the myeloma cells. Examples of culture media to be used for the above cell fusion include RPMI1640 medium and MEM culture medium suitable for the growth of the above myeloma cell lines, and the conventional culture medium used for this type of cell culture, and a serum supplement such as fetal calf serum (FCS) may be added.
In cell fusion, designated amounts of the above immunized cells and the myeloma cells are mixed well in the above culture medium, to which a PEG solution previously heated to about 37xc2x0 C., for example a PEG solution with a mean molecular weight of about 1000 to 6000, is added at a concentration of 30 to 60% (w/v) and mixed to obtain the desired fusion cells (hybridomas). Then by repeating the sequential addition of a suitable culture medium and centrifugation to remove the supernatant, cell fusion agents etc. which are undesirable for the growth of the hybridoma can be removed.
Said hybridoma is selected by culture in a conventional selection medium, for example, HAT medium (a culture medium containing hypoxanthine, aminopterin, and thymidine). Culturing in HAT medium is continued generally for a period of time sufficient to effect killing of the cells other than the desired hybridoma (non-fusion cells), generally several days to several weeks. The conventional limiting dilution method is conducted in which the hybridomas that produce the desired antibody are screened and cloned.
In addition to obtaining the above hybridoma by immunizing an animal other than human with an antigen, it is also possible to sensitize human lymphocytes in vitro with a desired antigen or desired antigen-expressing cells, and the resulting sensitized B lymphocytes are fused with a human myeloma cell, for example U266, to obtain a desired human antibody having the activity of binding to desired antigen or desired antigen-expressing cells (see Japanese Post-examined Patent Publication (Kokoku) 1(1989)-59878). Furthermore, a transgenic animal having a repertoire of all human antibody genes is immunized with an antigen or an antigen-expressing cells to obtain a desired human antibody in the method described above (see International Patent Publication WO 93/12227, WO 92/03918, WO 94/02602, WO 94/25585, WO 96/34096 and WO 96/33735).
The monoclonal antibody-producing hybridomas thus constructed can be subcultured in a conventional culture medium, or can be stored for a prolonged period of time in liquid nitrogen.
In order to obtain monoclonal antibodies from said hybridoma, a method can be used in which said hybridoma is cultured in a conventional method and an antibody is obtained in a supernatant, or a method in which the hybridoma is administered to and grown in a mammal compatible with said hybridoma and an antibody is obtained in the ascites. The former method is suitable for obtaining high-purity antibodies, whereas the latter is suitable for a large scale production of antibodies.
Specifically a hybridoma producing anti-IL-6 receptor antibody can be constructed using the method disclosed in Japanese Unexamined Patent Publication (Kokai) 3(1989)-139293. It can be conducted by a method in which the PM-1 antibody-producing hybridoma that was internationally deposited under the provisions of the Budapest Treaty as FERM BP-2998 on Jul. 10, 1990 with the National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, of 1-3, Higashi 1-chome, Tsukuba-shi, Ibaraki pref., Japan, is intraperitoneally injected to BALB/c mice to obtain the ascites from which the PM-1 antibody is purified, or a method in which said hybridoma is cultured in a suitable culture medium such as RPMI1640 medium containing 10% fetal bovine serum and 5% BM-Condimed H1 (manufactured by Boehringer Mannheim), the hybridoma SFM medium (manufactured by GIBCO-BRL), the PFHM-II medium (manufactured by GIBCO-BRL) and the like, and the PM-1 antibody can be purified from the supernatant.
A recombinant antibody which was produced by a gene recombination technology, in which an antibody gene was cloned from the hybridoma and integrated into a suitable vector, which transformed host cells, can be used in the present invention as monoclonal antibody (see, for example, Borrebaeck C. A. K., and Larrick J. W. THERAPEUTIC MONOCLONAL ANTIBODIES, published in the United Kingdom by MACMILLAN PUBLISHERS LTD. 1990).
Specifically, mRNA encoding a variable region (V) of a desired antibody is isolated from antibody-producing cells such as a hybridoma. The isolation of mRNA is conducted by preparing total RNA using, for example, a known method such as the guanidine ultracentrifuge method (Chirgwin, J. M. et al., Biochemistry (1979) 18, 5294-5299), the AGPC method (Chomczynski, P. et al., Anal. Biochem. (1987) 162, 156-159), and then mRNA is purified from the total RNA using the mRNA Purification kit (manufactured by Pharmacia) and the like. Alternatively, mRNA can be directly prepared using the Quick Prep mRNA Purification Kit (manufactured by Pharmacia).
cDNA of a V region of an antibody may be synthesized from the mRNA using a reverse transcriptase. cDNA may be synthesized using an AMV Reverse Transcriptase First-strand cDNA Synthesis Kit and the like. Alternatively, for the synthesis and amplification of CDNA, a 5xe2x80x2-Ampli FINDER RACE Kit (manufactured by Clontech) and a 5xe2x80x2-RACE method (Frohman, M. A. et al., Proc. Natl. Acad. Sci. USA (1988) 85, 8998-9002; Belyavsky, A. et al., Nucleic Acids Res. (1989) 17, 2919-2932) that employs polymerase chain reaction (PCR) may be used. A desired DNA fragment is purified from the PCR product obtained and may be ligated to vector DNA. Moreover, a recombinant vector is constructed therefrom and then is transformed into E. coli etc., from which colonies are selected to prepare a desired recombinant vector. The nucleotide sequence of a desired DNA may be confirmed by a known method such as the dideoxy method.
Once the DNA encoding a V region of a desired antibody has been obtained, it may be ligated to DNA encoding a constant region (C region) of a desired antibody, which is then integrated into an expression vector. Alternatively, a DNA encoding a V region of an antibody may be integrated into an expression vector which already contains DNA encoding a C region of an antibody.
In order to produce an antibody for use in the present invention, an antibody gene is integrated as described below into an expression vector so as to be expressed under the control of an expression regulatory region, for example an enhancer and/or a promoter. Subsequently, the expression vector may be transformed into a host cell and the antibody can then be expressed therein.
In accordance with the present invention, artificially altered recombinant antibody such as chimeric antibody and humanized antibody can be used for the purpose of lowering heterologous antigenicity against humans. These altered antibody can be produced using known methods.
Chimeric antibody can be obtained by ligating the thus obtained DNA encoding a V region of antibody to a DNA encoding a C region of a human antibody, which is then integrated into an expression vector and transformed into host cell for production of the antibody therein (see European Patent Application EP 125023, and International Patent Publication WO 92/19759). Using this known method, useful chimeric antibody for the present invention can be obtained.
For example, the plasmid that contains DNA encoding the L chain V region or the H chain V region of chimeric PM-1 antibody was designated as pPM-k3 or pPM-h1, respectively, and E. coli having the plasmid has been internationally deposited under the provisions of the Budapest Treaty as NCIMB 40366 and NCIMB 40362, respectively, on Feb. 11, 1991 with the National Collections of Industrial and Marine Bacteria Limited.
Humanized antibody which is also called reshaped human antibody has been made by grafting the complementarity determining regions (CDRs) of an antibody of a mammal other than the human, for example mouse antibody, into CDRs of a human antibody. The general recombinant DNA technology for preparation of such antibodies is also known (see European Patent Application EP 125023 and International Patent Publication WO 92-19759).
Specifically, a DNA sequence which was designed to ligate the CDRs of a mouse antibody with the framework regions (FRs) of a human antibody is synthesized from several divided oligonucleotides having sections overlapping with one another at the ends thereof. The DNA thus obtained is ligated to the DNA encoding the C region of human antibody and then is integrated into an expression vector, which is transformed into host cells for antibody production (see European Patent Application EP 239400 and International Patent Publication WO 92-19759).
For the FRs of a human antibody ligated to CDR, the complementarity determining region that forms a favorable antigen binding structure is selected. When desired, amino acids in the framework region of the antibody variable region may be substituted so that the complementarity determining region of reshaped human antibody may form an appropriate antigen binding structure (Sato, K. et al., Cancer Res. (1993) 53, 851-856).
For example, for chimeric antibody or humanized antibody, a C region of human antibody is used. As the C region of human antibody, there can be mentioned Cxcex3, and Cxcex31, Cxcex32, Cxcex33, and Cxcex34, for example, can be used. The C region of human antibody may be modified to improve the stability of antibody or the production thereof.
Chimeric antibody consists of the variable region of antibody derived from a mammal other than the human and the C region derived from human antibody, whereas humanized antibody consists of the complementarity determining regions of an antibody derived from a mammal other than the human and the framework regions and the C region of antibody derived from a human antibody. Accordingly, antigenicity thereof in the human body has been reduced so that they are useful as antibodies for use in the present invention.
A preferred embodiment of the humanized antibody for use in the present invention includes humanized PM-1 antibody (see International Patent Publication WO 92-19759).
Antibody genes constructed as described above may be expressed and the product is obtained in known methods. In the case of mammalian cells, expression may be accomplished using a vector containing a conventionally used useful promoter, the antibody gene to be expressed, and DNA in which the poly A signal has been operably linked at 3xe2x80x2 downstream thereof or a vector containing said DNA. Examples of the promoter/enhancer include human cytomegalovirus immediate early promoter/enhancer.
Additionally, as the promoter/enhancer which can be used for expression of antibody for use in the present invention, there are viral promoters/enhancers such as retrovirus, polyoma virus, adenovirus, and simian virus 40 (SV40), and promoters/enhancers derived from mammalian cells such as human elongation factor 1xcex1 (HEF1xcex1).
For example, expression may be readily accomplished by the method of Mulligan et al. (Mulligan, R. C. et al., Nature (1979) 277, 108-114) when SV40 promoter/enhancer is used, or by the method of Mizushima et al. (Mizushima, S. and Nagata, S. Nucleic Acids Res. (1990) 18, 5322) when HEF1xcex1 promoter/enhancer is used.
In the case of E. coli, expression may be conducted by operably linking a conventionally used useful promoter, a signal sequence for antibody secretion, and an antibody gene to be expressed, followed by expression thereof. As the promoter, for example, there can be mentioned lacz promoter and araB promoter. The method of Ward et al. (Ward, E. S. et al., Nature (1989) 341, 544-546; Ward, E. S. et al., FASEB J. (1992) 6, 2422-2427) may be used when lacz promoter is used, and the method of Better et al. (Better, M. et al., Science (1988) 240, 1041-1043) may be used when araB promoter is used.
As the signal sequence for antibody secretion, when produced in the periplasm of E. coli, the pelB signal sequence (Lei, S. P. et al., J. Bacteriol. (1987) 169, 4379-4383) can be used. After separating the antibody accumulated in the periplasm, the structure of the antibody is appropriately refolded before use (see, for example, WO 96/30394).
As an origin of replication, there can be used those derived from SV40, polyoma virus, adenovirus, bovine papilloma virus (BPV) and the like. Furthermore, for the amplification of the gene copy number in the host cell system, expression vectors can include as selectable markers an aminoglycoside phospho transferase (APH) gene, a thymidine kinase (TK) gene, E. coli xanthine guaninephosphoribosyl transferase (Ecogpt) gene, a dihydrofolate reductase (dhfr) gene and the like.
For the production of antibody for use in the present invention, any production system can be used. The production system of antibody preparation comprises the in vitro or the in vivo production system. As the in vitro production system, there can be mentioned a production system which employs eukaryotic cells and the production system which employs prokaryotic cells.
When the eukaryotic cells are used, there are the production systems which employ animal cells, plant cells, and fungal cells. Known animal cells include (1) mammalian cells such as CHO cells, COS cells, myeloma cells, baby hamster kidney (BHK) cells, HeLa cells, and Vero cells, (2) amphibian cells such as Xenopus oocytes, or (3) insect cells such as sf9, sf21, and Tn5. Known plant cells include, for example, those derived from Nicotiana tabacum, which may be subjected to callus culture. Known fungal cells include yeasts such as the genus Saccharomyces, more specifically Saccharomyces cereviceae, or filamentous fungi such as the genus Aspergillus, more specifically Aspergillus niger. 
When prokaryotic cells are used, there are the production systems which employ bacterial cells. Known bacterial cells include Escherichia coli (E. coli), and Bacillus subtilis. 
By transformation a gene for a desired antibody into these cells and culturing the transformed cells in vitro, the antibody can be obtained. Culturing is conducted in the known methods. For example, as the culture medium, DMEM, MEM, RPMI1640, and IMDM can be used, and serum supplements such as fetal calf serum (FCS) may be used in combination. In addition, antibodies may be produced in vivo by injection of cells transformed by antibody gene into the abdominal cavity of an animal and the like.
As in vivo production systems, there can be mentioned those which employ animals and those which employ plants. When animals are used, there are the production systems which employ mammals and insects.
As mammals, goats, pigs, sheep, mice, and cattle can be used (Vicki Glaser, SPECTRUM Biotechnology Applications, 1993). Also as insects, silkworms can be used.
When plants are used, tabacco, for example, can be used.
Antibody genes are transformed into these animals or plants, and the antibodies are produced in such animals or plants, and recovered. For example, an antibody gene is inserted into the middle of the gene encoding protein which is inherently produced in the milk such as goat xcex2 casein to prepare fusion genes. DNA fragments containing the fusion gene into which the antibody gene has been inserted are injected into a goat embryo, and the embryo is transferred into a female goat. The desired antibody is obtained from the milk produced by the transgenic goat borne to the goat who received the embryo or the offspring thereof. In order to increase the amount of milk containing the desired antibody produced by the transgenic goat, hormones may be given to the transgenic goat as appropriate. (Ebert, K. M. et al., Bio/Technology (1994) 12, 699-702).
When silkworms are used, baculovirus into which a desired antibody gene has been inserted is infected to the silkworm, and the desired antibody can be obtained from the body fluid of the silkworm (Maeda, S. et al., Nature (1985) 315, 592-594). Moreover, when tabacco is used, the desired antibody gene is inserted into an expression vector for plants, for example pMON 530, and then the vector is infected to a bacterium such as Agrobacterium tumefaciens. The bacterium is then infected to tabacco such as Nicotiana tabacum to obtain the desired antibody from the leaves of the tabacco (Julian, K.-C. Ma et al., Eur. J. Immunol. (1994) 24, 131-138).
When antibody is produced in vitro or in vivo production systems, as described above, DNA encoding the heavy chain (H chain) or the light chain (L chain) of antibody may be separately integrated into an each expression vector and the hosts are transformed simultaneously, or DNA encoding the H chain and the L chain may be integrated into a single expression vector and a host is transformed therewith (see International Patent Publication WO 94-11523).
Antibodies for use in the present invention may be antibody fragments or modified versions thereof as long as they are preferably used. For example, as fragments of antibody, there may be mentioned Fab, F(abxe2x80x2)2, Fv or single-chain Fv (scFv) in which Fv""s of H chain and L chain were ligated via a suitable linker.
Specifically antibodies are treated with an enzyme, for example, papain or pepsin, to produce antibody fragments, or genes encoding these antibody fragments are constructed, and then integrated into an expression vector, which is expressed in a suitable host cell (see, for example, Co, M. S. et al., J. Immunol. (1994) 152, 2968-2976; Better, M. and Horwitz, A. H., Methods in Enzymology (1989) 178, 476-496; Plueckthun, A. and Skerra, A., Methods in Enzymology (1989) 178, 476-496; Lamoyi, E., Methods in Enzymology (1986) 121, 652-663; Rousseaux, J. et al., Methods in Enzymology (1986) 121, 663-669; Bird, R. E. et al., TIBTECH (1991) 9, 132-137).
scFv can be obtained by ligating the V region of H chain and the V region of L chain of antibody. In the scFv, the V region of H chain and the V region of L chain are preferably ligated via a linker, preferably a peptide linker (Huston, J. S. et al., Proc. Natl. Acad. Sci. USA (1988) 85, 5879-5883). The V region of H chain and the V region of L chain in the scFv may be derived from any of the above-mentioned antibodies. As the peptide linker for ligating the V regions, any single-chain peptide comprising, for example, 12-19 amino acid residues may be used.
DNA encoding scFv can be obtained using DNA encoding the H chain or the H chain V region of the above antibody and DNA encoding the L chain or the L chain V region of the above antibody as the template by amplifying the portion of the DNA encoding the desired amino acid sequence among the above sequences by the PCR technique with the primer pair specifying the both ends thereof, and by further amplifying the combination of DNA encoding the peptide linker portion and the primer pair which defines that both ends of said DNA be ligated to the H chain and the L chain, respectively.
Once DNAs encoding scFv are constructed, an expression vector containing them and a host transformed with said expression vector can be obtained by the conventional methods, and scFv can be obtained using the transformed host by the conventional methods.
These antibody fragments can be produced by obtaining the gene thereof in a similar manner to that mentioned above and by allowing it to be expressed in a host. xe2x80x9cAntibodyxe2x80x9d as used in the claim of the present application encompasses these antibody fragments.
As modified antibodies, antibodies associated with various molecules such as polyethylene glycol (PEG) can be used. xe2x80x9cAntibodyxe2x80x9d as used in the claim of the present application encompasses these modified antibodies. These modified antibodies can be obtained by chemically modifying the antibodies thus obtained. These methods have already been established in the art.
Antibodies produced and expressed as described above can be separated from the inside or outside of the host cell and then may be purified to homogeneity. Separation and purification of the antibody for use in the present invention may be accomplished by affinity chromatography. As the column used for such affinity chromatography, there can be mentioned Protein A column and Protein G column. Examples of the carriers used in the Protein A column are Hyper D, POROS, Sepharose F. F. and the like. Alternatively, methods for separation and purification conventionally used for proteins can be used without any limitation. Separation and purification of the antibody for use in the present invention may be accomplished by combining, as appropriate, chromatography other than the above-mentioned affinity chromatography, filtration, ultrafiltration, salting-out, dialysis and the like. Chromatography includes, for example, ion exchange chromatography, hydrophobic chromatography, gel-filtration and the like. These chromatographies can be applied into high performance liquid chromatography (HPLC). Alternatively, reverse-phase HPLC can be used.
The concentration of antibody obtained in the above can be determined by the measurement of absorbance or by the enzyme-linked immunosorbent assay (ELISA) and the like. Thus, when absorbance measurement is employed, a sample is appropriately diluted with PBS(xe2x88x92) and then the absorbance is measured at 280 nm, followed by calculation using the absorption coefficient of 1.35 OD at 1 mg/ml. When the ELISA method is used, measurement is conducted as follows. Thus, 100 xcexcl of goat anti-human IgG (manufactured by TAGO) diluted to 1 xcexcg/ml in 0.1 M bicarbonate buffer, pH 9.6, is added to a 96-well plate (manufactured by Nunc), and is incubated overnight at 4xc2x0 C. to immobilize the antibody. After blocking, 100 xcexcl each of appropriately diluted antibody of the present invention or a sample containing the antibody, or 100 xcexcl of human IgG (manufactured by CAPPEL) as the standard is added, and incubated at room temperature for 1 hour.
After washing, 100 xcexcl of 5000-fold diluted alkaline phosphatase-labeled anti-human IgG antibody (manufactured by BIO SOURCE) is added, and incubated at room temperature for 1 hour. After washing, the substrate solution is added and incubated, followed by the measurement of absorbance at 405 nm using the MICROPLATE READER Model 3550 (manufactured by Bio-Rad) to calculate the concentration of the desired antibody.
The altered IL-6 for use in the present invention has an activity of binding to IL-6 receptor and does not transmit the biological activity of IL-6. Thus, the altered IL-6, though it competes with IL-6 for binding to IL-6 receptor, does not transmit the biological activity of IL-6, and thereby it blocks signal transduction by IL-6.
Altered IL-6 may be constructed through the introduction of mutation by replacing amino acid residues of the amino acid sequence of IL-6. IL-6, the source of the altered IL-6, may be of any origin, but when the antigenicity is to be considered, it is preferably human IL-6.
Specifically, the secondary structure of IL-6 is predicted using a known molecular modeling program of the amino acid sequence, for example WHATIF (Vriend et al., J. Mol. Graphics (1990), 8, 52-56), and the overall effects on the amino acid residue to be replaced is evaluated. After an appropriate amino acid residue was determined, mutation is introduced by the conventionally used polymerase chain reaction (PCR) method using a vector containing the nucleotide sequence encoding human IL-6 gene thereby to obtain a gene encoding altered IL-6. This is then integrated, as desired, into an appropriate expression vector, from which altered IL-6 can be obtained according to the expression, production and purification of said recombinant antibody.
Specific examples of the altered IL-6 are disclosed in Brakenhoff et al., J. Biol. Chem. (1994) 269, 86-93, and Savino et al., EMBO J. (1994) 13, 1357-1367, WO 96-18648, and WO 96-17869.
The partial peptides of IL-6 or IL-6 receptor for use in the present invention have an activity of binding to IL-6 receptor or IL-6, respectively, and does not transmit the biological activity of IL-6. Thus, the partial peptides of IL-6 or IL-6 receptor bind to IL-6 receptor or IL-6, respectively, and thereby capture it. As a result, they do not transmit the biological activity of IL-6, and block signal transduction of IL-6.
The partial peptides of IL-6 or the IL-6 receptor are peptides comprising some or all of the amino acid sequence of the region involved in the binding to IL-6 and IL-6 receptor in the amino acid sequence of IL-6 or IL-6 receptor. Such peptides generally comprises 10-80, preferably 20-50, more preferably 20-40 amino acid residues.
The partial peptides of IL-6 or the IL-6 receptor can be constructed by specifying the region involved in the binding to IL-6 and IL-6 receptor in the amino acid sequence of IL-6 or IL-6 receptor, and by producing some or all of the amino acid sequence by a conventional method such as a genetic engineering technology or a peptide synthesis method.
In order to produce the partial peptides of IL-6 or IL-6 receptor by a genetic engineering technology, the DNA sequence encoding the desired peptide is integrated into an expression vector, from which the peptide can be obtained by the expression, production, and purification of said recombinant antibody.
Production of the partial peptide of IL-6 or IL-6 receptor by the peptide synthesis method can be effected using a method commonly used in peptide synthesis such as the solid phase synthesis or the liquid phase synthesis.
Specifically the method described in Zoku-Iyakuhin no Kaihatsu (Sequel to Development of Pharmaceuticals), Vol. 14, Peputido Gousei (Peptide Synthesis), edited by Haruaki Yajima, Hirokawa Shoten, 1991, may be used. The solid phase synthesis method used includes, for example, a reaction in which an amino acid corresponding to the C-terminal of the peptide to be synthesized is coupled to a support which is insoluble in organic solvents, and then an amino acid in which xcex1-amino group or a side chain functional group has been protected with an appropriate protecting group is condensed one amino acid at a time from the C-terminal to the N-terminal direction, and a reaction in which said protecting group of the xcex1-amino group of the amino acid or the peptide coupled to the resin is eliminated is alternately repeated to elongate the peptide chain. The solid phase peptide synthesis methods are divided into the Boc method and the Fmoc method depending on the type of protecting group to be used.
After the synthesis of the desired peptide is complete, a deprotection reaction and a reaction for cleaving the peptide chain from the support is carried out. For cleavage from the peptide chain, hydrogen fluoride or trifuluoromethanesulfonic acid in the Boc method and TFA in the Fmoc method are generally used. In the Boc method, for example, the above peptide resin is treated in hydrogen fluoride in the presence of anisole. Subsequently, the protecting group is eliminated and the peptide is recovered by cleaving from the support. By lyophilizing this, crude peptide can be obtained. On the other hand, in the Fmoc method, TFA, for example, is used in a manner similar to the above to effect the deprotection reaction and the cleavage reaction of the peptide from the support.
The crude peptide thus obtained can be applied to HPLC for its separation and purification. Its elution can be carried out in a water-acetonitrile solvent system that is commonly used for protein purification under an optimum condition. The fraction corresponding to the peak of the profile of the chromatography obtained is collected and lyophilized. The peptide fraction thus purified is identified by subjecting it to the analysis of molecular weight by mass spectroscopy, the analysis of amino acid composition, or the analysis of amino acid sequence, and the like.
Specific examples of the IL-6 partial peptide or the IL-6 receptor partial peptide are disclosed in Japanese Unexamined Patent Publication (Kokai) 2(1990)-188600, Japanese Unexamined Patent Publication (Kokai) 7(1995)-324097, Japanese Unexamined Patent Publication (Kokai) 8(1996)-311098, and U.S. Pat. No. 5,210,075.
The activity of the IL-6 antagonist for use in the present invention can be evaluated using a conventionally known method. Specifically, the IL-6-dependent cell MH60.BSF2 is cultured, to which IL-6 is added, and the activity can be evaluated using the incorporation of 3H-thymidine into the IL-6-dependent cell in the coexistence of the IL-6 antagonist. Alternatively, evaluation can be effected by culture of U266, a IL-6 receptor-expressing cell, adding thereto 125I-labeled IL-6 and an IL-6 antagonist at the same time, and then by determining the 125I-labeled IL-6 bound to the IL-6 receptor-expressing cell. In the above assay system, a negative control group containing no IL-6 antagonists, in addition to the group in which an IL-6 receptor antagonist is present, is set up, and the results obtained for them are compared to evaluate the IL-6-inhibiting activity of the IL-6 receptor antagonist.
In order to confirm the effects accomplished by the present invention, an IL-6 antagonist for use in the present invention is administered to animals that developed inflammatory bowel disease by the injection of CD4-positive and CD45RB-strong positive cells (CD4+CD45RBhigh cells), and the effect of suppressing weight loss and of improving the inflammatory bowel disease score can be evaluated. As additional effects of the present invention, there are effects of suppressing anorexia, reducing abdominal pains, ameliorating diarrhea, or preventing recurrence of inflammatory bowel disease.
The CD4+CD45RBhigh cells that are transferred into animals by an IL-6 antagonist may be isolated by using, for example, the method described in the Example below. Animals from which CD4+CD45RBhigh cells are derived may be those commonly used in experiments such as mice and rats.
As described in the Example below, in the animals that developed inflammatory bowel disease, the administration of IL-6 receptor antibody resulted in suppression of weight loss and improvement in the inflammatory bowel disease score, and thus it was revealed that IL-6 antagonists such as anti-IL-6 receptor antibody exert a therapeutic effect on inflammatory bowel disease.
The subject to be treated in the present invention is mammals. The subject to be treated is preferably humans.
The preventive or therapeutic agents of the present invention may be administered, either orally or parenterally, systemically or locally. For example, intravenous injection such as drip infusion, intramuscular injection, intraperitoneal injection, subcutaneous injection, suppositories, intestinal lavage, oral enteric coated tablets, and the like can be selected, and the method of administration may be chosen, as appropriate, depending on the age and the conditions of the patient. The effective dosage is chosen from the range of 0.01 mg to 100 mg per kg of body weight per administration. Alternatively, the dosage in the range of 1 to 1000 mg, preferably 5 to 50 mg per patient may be chosen.
The preventive or therapeutic agents for inflammatory bowel disease of the present invention may contain pharmaceutically acceptable carriers or additives depending on the route of administration. Examples of such carriers or additives include water, a pharmaceutical acceptable organic solvent, collagen, polyvinyl alcohol, polyvinylpyrrolidone, a carboxyvinyl polymer, sodium carboxymethylcellulose, polyacrylic sodium, sodium alginate, water-soluble dextran, sodium carboxymethyl starch, pectin, methyl cellulose, ethyl cellulose, xanthan gum, Arabic gum, casein, gelatin, agar, diglycerin, propylene glycol, polyethylene glycol, Vaseline, paraffin, stearyl alcohol, stearic acid, human serum albumin (HSA), mannitol, sorbitol, lactose, a pharmaceutically acceptable surfactant and the like. Additives used are chosen from, but not limited to, the above or combinations thereof depending on the dosage form.
The subject disease to be treated of the present invention is inflammatory bowel disease. Inflammatory bowel disease includes ulcerative colitis and Crohn""s disease. These diseases occur mostly in young people about 20 years of age, and little is known, even today, about the causative antigens or the mechanism of inflammatory pathology. However, extensive research is under way to elucidate them with various cells and cytokines.
In the last few years, progress has been observed in the analysis of cells that cause inflammatory bowel disease. Thus, it has become apparent that the animal model of inflammatory bowel disease can be constructed by transfer of purified CD4-positive, CD45RB-strong positive cells (CD4+CD45RBhigh) to immunodeficient mice (SCID mice) (Morrissey, P. J. et al., J. Exp. Med. (1993) 178, 237-244; Leach, M. W. et al., Am. J. Pathol. (1996) 148, 1503-1515; Aranda, R. et al., J. Immunol. (1997) 158, 3464-3473).
On the other hand, it has been shown that CD4-positive, CD45RB-weak positive cells (CD4+CD45RBlow) cannot induce inflammatory bowel disease, and it rather suppresses the induction of inflammatory bowel disease by CD4-positive, CD45RB-strong positive cells (Powrie, F. R. et al., J. Exp. Med. (1994) 179, 589-600). The amount of CD45RB expression per cell is known to correlate to the cytokine production pattern. Thus, it is believed that CD4-positive, CD45RB-strong positive cells are type 1 helper (Th1)-like cells that produce IFN-xcex3 and TNF-xcex1, whereas CD4-positive, CD45RB-weak positive cells are type 2 helper cells (Th2)-like that produce IL-4, IL-10, and the like (Lee, W. et al., J. Immunol. (1990) 144, 3288-3295).
Thus, it is thought that the onset of IBD is most probably associated with the disturbed balance of Th1 and Th2, and this has been endorsed by the fact that chronic enteritis resembling human ulcerative colitis developed in IL-10 deficient mouse that was made by the gene targeting method (Kuhn, R. et al. Cell (1993) 75, 263-274).
Model animals used in the Example are very similar to patients with ulcerative colitis and Crohn""s disease in the histoloical features of the colon (Leach, M. W. et al., Am. J. Pathol. (1996) 148, 1503-1515). In ulcerative colitis, lesions are often seen in extensive succession from the rectum and the epithelia of mucosa are specifically injured. In the present model, clinical pathologies are very similar in that the injured sites covers a wide area, though mainly localized in colon, and crypt extends.
On the other hand, Crohn""s disease is a full thickness inflammation, not localized in the mucosa, and is disseminated in anywhere in the alimentary canal from the oral cavity to the anus. Histologically, it is characterised by inflammation of noncaseating granuloma. This model is very similar to Crohn""s disease in that inflammation not localized in the mucosal layer is found, where macrophage, lymphocytes, and multinuclear giant cells accumulate, and often takes the form of granuloma, and that crypt abscess is seldom found.
Thus, cases in which the features of ulcerative colitis and Crohn""s disease coexist have been reported so far in the clinical research (Tanaka, M. et al, Hepato-gastroenterology (1990) 37, 18-31). In inflammatory bowel disease, enhanced expression of the major histocompatibility complex class II is found in the epithelium (Trejdosiewicz, L. K. et al., Dig. Dis. Sci. (1989) 34, 1449-1456), and the same holds true for the present model. In this model, characteristic thickening of the epithielial tissue appears, which is believed to be associated with enhanced cellular growth found in patients with ulcerative colitis (Serafini, E. P. et al., Gut (1981) 22, 648-652).
The present model is very similar to clinical inflammatory bowel disease, and may induce weight loss in severe cases. In an experiment using the present model, histological damages were markedly ameliorated and weight loss was not observed, which indicates that an IL-6 antagonist exhibits a therapeutic effect on inflammatory bowel disease such as ulcerative colitis or Crohn""s disease.